An infrared heat-image camera is aimed at a hot surface not perpendicular thereto but instead in a direction almost parallel to the surface, presenting to the camera a heat image of the surface not cartesian but instead highly distorted in accordance with the laws of optical perspective. The camera's output data is correspondingly non-cartesian and distorted with respect to organization and content, but the data is applied to a computer which transforms it to cartesian organization and corrects content, and then a corrected cartesian display is generated, simulating the heat image which would be presented to a perpendicularly aimed camera. Alternatively, the camera's scanning mechanisms are programmed to follow a non-cartesian scanning schedule, the geometry of which itself causes the camera output data to have the cartesian organization of a perpendicularly aimed camera. Preferably, the scanning schedule is modified to effect transformation to cartesian organization in only one direction, and transformation to cartesian organization in the other direction is computer-performed.